多层螺旋CT在心肌桥诊断中的应用及优势

目的 探讨多层螺旋CT(MSCT)在心肌桥中的诊断能力.方法 对51例临床怀疑为冠状动脉粥样硬化性心脏病的患者进行了MSCT、常规冠状动脉造影(CAG)以及血管内超声检查(将后2种检查方法统称为创伤性技术),共82支冠状动脉,其中的80支冠状动脉无明显伪影,可供评价.分别统计MSCT对心肌桥检出的敏感度、特异度和准确度.观察者间的一致件检验采用Cohen Kappa检验方法.结果CAG及血管内超声共发现26例心肌桥,所有心肌桥均发生于左前降支中段附近.MSCT正确检出26例前降支心肌桥巾的23例,其敏感度88%(23/26),特异度96%(52/54),准确度94%(75/80),2名医师对心肌桥的检出Kappa值为0.62.MSCT尚检出2例心肌桥,为创伤性技术所漏诊.将创伤性技术和MSCT综合结果作对照,则MSCT心肌桥检出的敏感度、特异度和准确度分别为89%(25/28)、91%(21/23)和90%(46/51).结论MSCT作为一种无创性成像方法应用于心肌桥的诊断,方法可行,结果可靠.     

Cone beam CT image artefacts related to head motion simulated by a robot skull: visual characteristics and impact on image quality

Objectives:

The aim of this study was to assess artefacts and their impact on cone beam CT (CBCT) image quality (IQ) after head motion simulated by a robot skull.

Methods:

A fully dentate human skull incorporated into a robot simulated pre-determined patient movements. Ten head motion patterns were selected based on the movement of the C-arm of the CBCT units (no motion as reference). Three CBCT units were used [a three-dimensional eXam (K) (KaVo Dental GmbH, Biberach, Germany), a Promax 3D MAX (P) (Planmeca Oy, Helsinki, Finland) and a Scanora^® 3D (S) (Soredex Oy, Tuusula, Finland)]. Axial images were qualitatively assessed at three levels: mental foramen (MF), infraorbital foramen and supraorbital foramen, and artefacts characterized as stripe-like, double contours, unsharpness or ring-like. A 100 mm visual analogue scale (VAS) was used to quantitatively assess IQ. Cross-sectional images of the lower third molar and MF bilaterally were also evaluated by VAS. Four blinded examiners assessed the images.

Results:

For all units and motion patterns, stripe-like artefacts were the most common. The four observers agreed on the presence of at least one artefact type in 90% of the images. Axial images showed lower overall IQ after motion (VAS = 72.4 ± 24.0 mm) than reference images (VAS = 97.3 ± 2.6 mm). The most severe artefacts were seen at the MF level. For cross-sectional images, IQ was lowest after tremor. The mean IQ range was 74–89 and 57–90 for isolated (tilting, rotation and nodding) and combined (nodding + tilting and rotation + tilting) movements, respectively. IQ for MF was lower than for third molar for any movement except tremor.

Conclusions:

Head motion of any type resulted in artefacts in CBCT images. The impact on IQ depended on the region and level in the skull.     

Evaluation of a metal artifact reduction algorithm applied to post-interventional flat detector CT in comparison to pre-treatment CT in patients with acute subarachnoid haemorrhage

Objectives

Metal artefacts can impair accurate diagnosis of haemorrhage using flat detector CT (FD-CT), especially after aneurysm coiling. Within this work we evaluate a prototype metal artefact reduction algorithm by comparison of the artefact-reduced and the non-artefact-reduced FD-CT images to pre-treatment FD-CT and multi-slice CT images.

Methods

Twenty-five patients with acute aneurysmal subarachnoid haemorrhage (SAH) were selected retrospectively. FD-CT and multi-slice CT before endovascular treatment as well as FD-CT data sets after treatment were available for all patients. The algorithm was applied to post-treatment FD-CT. The effect of the algorithm was evaluated utilizing the pre-post concordance of a modified Fisher score, a subjective image quality assessment, the range of the Hounsfield units within three ROIs, and the pre-post slice-wise Pearson correlation.

Results

The pre-post concordance of the modified Fisher score, the subjective image quality, and the pre-post correlation of the ranges of the Hounsfield units were significantly higher for artefact-reduced than for non-artefact-reduced images. Within the metal-affected slices, the pre-post slice-wise Pearson correlation coefficient was higher for artefact-reduced than for non-artefact-reduced images.

Conclusion

The overall diagnostic quality of the artefact-reduced images was improved and reached the level of the pre-interventional FD-CT images. The metal-unaffected parts of the image were not modified.

Key Points

? After coiling subarachnoid haemorrhage, metal artefacts seriously reduce FD-CT image quality.? This new metal artefact reduction algorithm is feasible for flat-detector CT.? After coiling, MAR is necessary for diagnostic quality of affected slices.? Slice-wise Pearson correlation is introduced to evaluate improvement of MAR in future studies.? Metal-unaffected parts of image are not modified by this MAR algorithm.

     

Flat-panel detector volumetric CT for visualization of subarachnoid hemorrhage and ventricles: preliminary results compared to conventional CT

INTRODUCTION: The aim of this study was to compare flat-panel volumetric CT (VCT) to conventional CT (cCT) in the visualization of the extent of subarachnoid hemorrhage (SAH) and the width of the ventricles in patients with acute SAH. METHODS: Included in the study were 22 patients with an acutely ruptured cerebral aneurysm who received VCT during coil embolization. VCT image quality, the extent of SAH (using a modified Fisher score and total slice number with SAH visible) and the width of the ventricles (Evans index) were evaluated by two experienced neuroradiologists (RAD1 and RAD2) and compared to the findings on cCT. Ten patients undergoing VCT for reasons other than SAH served as negative controls. RESULTS: Interobserver agreement in rating image quality was excellent for cCT (Kendall W value 0.94) and good for VCT (0.74). SAH was identified by RAD1 and RAD2 on VCT images in all patients. The modified Fisher scores underestimated the extent of SAH on VCT images in comparison with cCT images. Pearson's correlation coefficient (r) regarding the number of image slices with SAH visible on cCT images compared with the number on VCT images was 0.85 for RAD1 and 0.84 for RAD2. The r value for the degree of interobserver agreement for the number of slices with SAH visible was 0.99 for cCT, and 0.95 for VCT images (n=19), respectively. The width of the ventricles measured in terms of the Evans Index showed excellent concordance between the modalities (r=0.81 vs. 0.82). CONCLUSION: Our preliminary results indicate that VCT is helpful in evaluating SAH in the angiography suite. Additionally, reliable evaluation of ventricle width is feasible. However, there are limitations with regard to the visibility of SAH on VCT images in comparison to cCT images.     

Multislice CT imaging of anomalous coronary arteries

The purpose of the present study was to evaluate the role of 16 multislice computed tomography (MSCT) to identify the origin of anomalous coronary arteries and to confirm their anatomic course in relation to the great vessels. Accuracy of coronary artery disease (CAD) detection was a secondary aim and was tested with conventional angiograms (CA) serving as standard of reference. Two hundred and forty-two consecutive patients referred for noninvasive coronary CT imaging were reviewed for the study. Sixteen patients (6.6%) with anomalous coronary arteries were detected and included as the study group. MSCT and CA images were analyzed in a blinded fashion for accuracy of anomalous artery origin and path detection. Results were compared in a secondary consensus evaluation. Accuracy ratios to detect CAD with MSCT in all vessels were calculated. Coronary anomalies for all 16 patients were correctly displayed on MSCT. CA alone achieved correct identification of the abnormality in only 53% (P=0.016). Sensitivity and specificity of MSCT to detect significantly stenosed vessels was 90 and 92%. 16-MSCT is accurate to delineate abnormally branching coronary arteries and allows sufficiently accurate detection of obstructive coronary artery disease in distal branches. It should therefore be considered as a prime non-invasive imaging tool for suspected coronary anomalies.     

Detection of pulmonary nodules by multislice computed tomography: improved detection rate with reduced slice thickness

The purpose of this study was to find out if the use of 1.25-mm collimated thin-slice technique helps to detect more small pulmonary lung nodules than the use of 5 mm. A total of 100 patient examinations that allowed a reconstruction of 1.25-mm slice thickness in addition to the standard of 5-mm slices were included in a prospective study. Acquisition technique included four rows of 1-mm slices. Two sets of contiguous images were reconstructed and compared with 1.25- and 5-mm slice thickness, respectively. Two radiologists performed a film-based analysis of the images. The size and the confidence of the seen nodules were reported. We did not perform a histological verification, according to the normal clinical procedure, although it would be optimal regarding research. Statistical analysis was performed by using longitudinal analysis described by Brunner and Langer [10]. In addition, sensitivity, specificity, negative predictive value and positive predictive value were calculated for each reader using the 1.25-mm sections as the gold standard. As an index for concordance the kappa value was used. A value of p<0.05 was regarded as significant. In 37 patients pulmonary nodules were detected. Twenty-four patients showed more than one nodule; among these, 7 patients had disseminated disease and were excluded from the study. Pulmonary nodules larger than 10 mm in size were equally well depicted with both modalities, whereas lesions smaller than 5 mm in size were significantly better depicted with 1.25 mm (p<0.05). Using 1.25 mm as the gold standard, sensitivity for 5-mm reconstruction interval was 88 and 86% for observers A and B, respectively. No false-positive results were reported for 5-mm sections. Interobserver agreement for nodule detection determined for 1.25-mm reconstruction intervals showed a k value of 0.753, indicating a good agreement, and 0.562 for 5-mm reconstruction intervals, indicating a moderate agreement. Brunner and Langer [10] analysis showed significant differences for slice thickness and no significant difference between the observers. Reduced slice thickness demonstrated an improvement of small nodule detection, confidence levels, and interobserver agreement. Application of thin-slice multidetector-row CT may raise the sensitivity for lung nodule detection, although the higher detection rate of smaller nodules has to be evaluated from a clinical perspective and remains problematic about how the detection of small nodules will effect patient outcome.     

MSCT诊断卵圆孔未闭

目的:探讨心电门控MSCT心脏成像检测卵圆孔未闭的可行性。方法:对124例患者行MSCT心脏成像,根据房间隔隧道样外观和心房间左向右分流来诊断PFO。结果:在MSCT上共发现29例PFO(23.4%)。在22例同时行经胸超声(TTE)和CT的患者中,以TTE作为金标准,根据房间隔内通道和分流,CT诊断PFO的敏感性、特异性分别为66.6%和93.7%,阳性预测值为80.0%,阴性预测值为88.2%。结论:MSCT能可靠地检测PFO。     

Sixteen-slice spiral CT versus MR imaging for the assessment of left ventricular function in acute myocardial infarction

The aim of this study was to assess global left ventricular (LV) function and regional wall motion using retrospectively ECG-gated 16-slice computed tomography (CT) in comparison with magnetic resonance imaging (MRI). Twenty-one patients (18 male, 65.5±8.6 years) with acute myocardial infarction underwent multislice spiral CT (MSCT) and MRI. From manually drawn endo- and epicardial contours, LV volumes including myocardial mass, peak filling rate (PFR), peak ejection rate (PER), time to PER (TPER) and time from end-systole to PFR (TPFR) were calculated. Regional wall motion was assessed from cine loops using a 16-segment model of the left ventricle. LV function was analyzed using the Bland–Altman method, Pearsons correlation coefficient, multivariate analysis and post hoc t tests. Regional wall motion was evaluated with weighted kappa-statistics. Multivariate analysis revealed significant differences for global LV function as determined by MSCT and MRI. Post hoc t-tests showed significant differences for end-diastolic volume (EDV), PFR and TPER (P<0.05), while there was a good agreement for the LV volumes with an ejection fraction of 46.9±8.4% for MSCT and 46.9±8.9% for MRI. PER, PFR, TPER and TPFR presented a poor correlation and a wide range of scattering between MSCT and MRI. Regional wall motion scores showed a good agreement with =0.791. Sixteen-slice spiral CT allows for reliable assessment of LV volumes, but is not yet suited for the evaluation of all functional parameters. Assessment of regional wall motion at rest is feasible.     

Ultra-low-dose coronary artery calcium screening using multislice CT with retrospective ECG gating

The aim of this study was to reduce radiation exposure in multislice CT (MSCT) coronary artery calcium screening using different tube settings, and to determinate its impact on the detection and quantification of coronary artery calcification. Forty-eight patients underwent routine MSCT coronary artery calcium scoring (Somatom VolumeZoom, Siemens, Forchheim, Germany) with retrospective ECG-gated data acquisition. Scanning was performed with a 4×2.5-mm collimation. In each patient data acquisition was performed twice using tube settings of 120 kVp with 133 mAs (protocol 1) and of 80 kVp with 300 mAs (protocol 2). Together with the 80-kVp protocol additional online ECG-related tube current modulation (ECG pulsing) was used. Three-millimeter overlapping slices (increment 1.5 mm) were calculated for each data set. Semi-automated calcium quantification was performed calculating absolute Ca-hydroxylapatite mass. In addition to patient examinations, the radiation exposure for both protocols was evaluated using computed tomography dose index (CTDI) phantom measurements. Protocol 2 showed a significantly lower patient radiation exposure than protocol 1 (0.72 vs 2.04 mSv; p<0.0001). The CTDI phantom measurements revealed a 65% reduction of radiation dose. Calcium scoring results of both protocols showed a high correlation (r=0.99; p<0.0001) for absolute Ca-Hydroxylapatite mass measurements. Using 80-kVp protocols patient radiation exposure can be significantly reduced in MSCT coronary artery calcium screening without affecting the detection and quantification of coronary artery calcification; therefore, this technique should be used with retrospective ECG-gated cardiac CT examinations in patients with regular sinus rhythm.     

多层螺旋CT对显示泌尿系微小结石的实验研究

目的 :评价多层螺旋CT(MSCT)在不同扫描条件下对泌尿系结石的显示率。方法 :5 1个不同大小取自患者的泌尿系结石 ,将结石分为 3组。A组 :大于 5mm(15个 ) ,B组 :3～ 5mm(9个 ) ,C组 :小于 3mm(2 7个 )。分别经设置不同扫描参数的单层螺旋CT(SSCT)和MSCT扫描。比较不同扫描参数设置下SSCT和MSCT的结石检出率 ,检验不同扫描层厚与检出结石数的关系。结果 :所有序列对A、B组的检出率均为 10 0 % (2 4/ 2 4) ,C组检出的结石数与扫描层厚呈明显负相关(MSCT :r=-0 .947,P <0 .0 1;SSCT :r =-0 .999,P <0 .0 1) ,检出的结石数随着扫描层厚变薄而增多。MSCT 5mm和 10mm层厚扫描 ,然后分别以 0 .62 5mm和 1.2 5mm层厚重建所得的图像 ,其质量及其显示出的结石数与MSCT相应同等薄层扫描 (0 .62 5mm和 1.2 5mm层厚扫描 )所得的结果完全一致。结论 :MSCT因其有效的薄层重建能力、超快的扫描速度以及极高的空间分辨率 ,在检测泌尿系小结石方面较SSCT具有明显优势。运用MSCT检测泌尿系结石值得临床广泛应用。     

超急性脑梗死首诊的多层螺旋CT表现

目的 探讨超急性期脑梗死的多层螺旋CT(multislice spiral computed tomography, MSCT)平扫表现.方法 回顾分析确诊的 19例超急性脑梗死病例,所有病例发病后1～6 h内进行第1次MSCT平扫检查,经发病后3 h～5 d复查MSCT或MRI确诊,观察分析MSCT平扫征象.结果 首次诊断超急性脑梗死17例,可疑诊断2例.MSCT平扫阳性表现主要有脑实质低密度征19例,局部脑肿胀征13例,脑动脉高密度征3例.结论 MSCT平扫对超急性脑梗死具有较高诊断价值.     

Electrocardiographic assistance in multidetector CT of thoracic disorders

ECG-synchronized multislice spiral CT (MSCT) allows a significant reduction of cardiac motion artefacts and as a result a virtually artefact-free display of intrathoracic structures. With their advantages in imaging geometry and continuous spiral image acquisition multislice CT scanners provide superior image quality and spatial resolution in these patients. Possible clinical applications for ECG assistance in MSCT include CT angiography of the coronary arteries, functional cardiac CT imaging and imaging of the cardiac valves, CT angiography of the aorta or pulmonary vascular tree as well as ECG-gated imaging of the lung parenchyma. Prospective ECG triggering and retrospectively ECG-gated image reconstruction comprise the technical corsage for reduction of pulsation artefacts in cardiac and other thoracic CT applications. In addition the development of time-optimised reconstruction algorithms for retrospective cardiac gating in 8- and 16 slice spiral CT scanners have enabled further improvements in temporal resolution. This overview describes the technique, its clinical indications and the merits of electrocardiographic assistance in MSCT of chest disorders.     

CT在下咽和喉部肿瘤及肿瘤样病变定性诊断中的价值

目的探讨增强CT扫描在下咽及喉部病变定性诊断中的作用。方法收集76例经手术病理证实的下咽和喉部肿瘤及肿瘤样病变的完整临床资料,其中恶性病变66例,良性病变10例。先行客观定量CT影像征象分析,数据采用逻辑回归分析,以判定能否用CT影像征象来鉴别下咽和喉部病变的良恶性。然后由2位放射学专家双盲判定全部病例,及由另2位放射学专家判断从中挑选的20例病例(10例良性病例与随机选取的10例恶性病例)的病变性质,判断观察者间CT在下咽和喉部病变定性诊断中的准确性及其一致性(Kappa值)。结果逻辑回归分析结果显示在所选取的12个变量中,只有病变发生部位及病变对邻近结构的侵犯情况有统计学意义,可用于诊断病变为恶性。其中病变对周围结构侵犯诊断下咽及喉部病变为恶性的敏感性为53%,特异性为80%,准确性为55%。当大部分病变为恶性时,2位观察者对病变性质的判断有中度一致性(Kappa=0.54),其准确性为84%。当20例中良恶性病例各半时,2位观察者对病变性质的判断一致性很差(Kappa=0.20),且其准确性略好于随机选择的概率。结论用CT影像特征难以判定下咽和喉部病变的性质。     

Sixteen-row multislice computed tomography in the assessment of pulmonary veins prior to ablative treatment: validation vs conventional pulmonary venography and study of reproducibility

The aim of this study was to validate multislice computed tomography (MSCT) venography measurements of pulmonary vein (PV) diameters vs conventional pulmonary venography (CPV), and to assess the reproducibility of MSCT data. The study included 21 consecutive patients with atrial fibrillation who were planned for cryothermal ablation of PVs. One day before ablation, all patients underwent CPV and contrast-enhanced non-gated MSCT venography. The MSCT was repeated 3 months after ablation. The CPV images of the treated PVs (n=40) were analyzed and compared with the results of MSCT measurements. Reproducibility of MSCT venography-based data was assessed by interobserver (n=84 PVs) and interexamination (n=44 PVs) variability. Pre-treatment PV diameters on MSCT and CPV showed good correlation (r=0.87, p<0.01; 18.9±.2.3 mm, 188.5±.2.4 mm, respectively). Interobserver agreement and interexamination reproducibility were good (r=0.91, r=0.82, respectively, p<0.01), with narrow limits of agreement (Bland and Altman method). The MSCT venography allows accurate and reproducible assessment of PVs. It can be used both in non-invasive planning of treatment for ablative therapy and in the follow-up of patients.     

Dental cone beam CT image quality possibly reduced by patient movement

Patient artefacts in dental cone beam CT scans can happen for various reasons. These range from artefacts from metal restorations to movement. An audit was carried out in the Glasgow Dental Hospital analysing how many scans showed signs of “motion artefact”, and then to assess if there was any correlation between patient age and movement artefacts. Specific age demographics were then analysed to see if these cohorts were at a higher risk of “movement artefacts”.     

Reproducibility of electron-beam CT measures of aortic valve calcification

RATIONALE AND OBJECTIVES: The authors performed this study to establish the interscan, interobserver, and intraobserver reproducibility of aortic valve calcification (AVC) measurements obtained with electron-beam computed tomography (CT). MATERIALS AND METHODS: The authors evaluated electron-beam CT scans from all patients who had undergone two serial examinations on the same day as part of a study of coronary artery calcification reproducibility. In patients in whom aortic valve calcium was identified at electron-beam CT, AVC scores were measured with both the Agatston and the volumetric methods, which were developed previously to quantify coronary calcium. RESULTS: Forty-four asymptomatic patients (mean age, 66 years +/- 9) with AVC at electron-beam CT were included in the analyses. AVC score reproducibility was excellent with both the Agatston and the volumetric methods (R2 = 0.99, P = .0001 for both), with median interscan variabilities of 7% and 6.2%, respectively. Interscan reproducibility was similar, whether the analysis included all scans or was restricted to those with scores greater than 10 or greater than 30. For the volumetric method, the median interobserver variability was 5% and the median intraobserver variability was 1%. CONCLUSION: The low interscan, interobserver, and intraobserver variabilities at electron-beam CT suggest that this method should be useful for the noninvasive monitoring of AVC changes over time and for assessing the efficacy of therapies aimed at slowing AVC accumulation.     

Evaluation of the effective dose of cone beam CT and multislice CT for temporomandibular joint examinations at optimized exposure levels

Objectives:

To compare the effective dose to patients from temporomandibular joint examinations using a dental CBCT device and a multislice CT (MSCT) device, both before and after dose optimization.

Methods:

A Promax^® 3D (Planmeca, Helsinki, Finland) dental CBCT and a LightSpeed VCT^® (GE Healthcare, Little Chalfont, UK) multislice CT were used. Organ doses and effective doses were estimated from thermoluminescent dosemeters at 61 positions inside an anthropomorphic phantom at the exposure settings in clinical use. Optimized exposure protocols were obtained through an optimization study using a dry skull phantom, where four observers rated image quality taken at different exposure levels. The optimal exposure level was obtained when all included criteria were rated as acceptable or better by all observers.

Results:

The effective dose from a bilateral examination was 184 µSv for Promax 3D and 113 µSv for LightSpeed VCT before optimization. Post optimization, the bilateral effective dose was 92 µSv for Promax 3D and 124 µSv for LightSpeed VCT.

Conclusions:

At optimized exposure levels, the effective dose from CBCT was comparable to MSCT.     

Assessment of global and regional left ventricular function using 64-slice multislice computed tomography and 2D echocardiography: a comparison with cardiac magnetic resonance

OBJECTIVES: To compare the assessment of global and regional left ventricular (LV) function using 64-slice multislice computed tomography (MSCT), 2D echocardiography (2DE) and cardiac magnetic resonance (CMR). METHODS: Thirty-two consecutive patients (mean age, 56.5+/-9.7 years) referred for evaluation of coronary artery using 64-slice MSCT also underwent 2DE and CMR within 48h. The global left ventricular function which include left ventricular ejection fraction (LVEF), left ventricular end diastolic volume (LVdV) and left ventricular end systolic volume (LVsV) were determine using the three modalities. Regional wall motion (RWM) was assessed visually in all three modalities. The CMR served as the gold standard for the comparison between 64-slice MSCT with CMR and 2DE with CMR. Statistical analysis included Pearson correlation coefficient, Bland-Altman plots and kappa-statistics. RESULTS: The 64-slice MSCT agreed well with CMR for assessment of LVEF (r=0.92; p<0.0001), LVdV (r=0.98; p<0.0001) and LVsV (r=0.98; p<0.0001). In comparison with 64-slice MSCT, 2DE showed moderate correlation with CMR for the assessment of LVEF (r=0.84; p<0.0001), LVdV (r=0.83; p<0.0001) and LVsV (r=0.80; p<0.0001). However in RWM analysis, 2DE showed better accuracy than 64-slice MSCT (94.3% versus 82.4%) and closer agreement (kappa=0.89 versus 0.63) with CMR. CONCLUSION: 64-Slice MSCT correlates strongly with CMR in global LV function however in regional LV function 2DE showed better agreement with CMR than 64-slice MSCT.     

Role of MDCT in evaluation of congenital and acquired anomalies of pulmonary venous drainage

Objective

This work aimed for detection of different congenital and acquired abnormalities affecting the pulmonary veins using multislice computed tomography (MSCT).

多层螺旋CT在肺动脉栓塞诊断中的应用价值

目的 研究多层螺旋CT在肺动脉栓塞诊断中的临床应用，着重研究亚段肺动脉栓塞的诊断价值。方法 共34例，下肢深静脉血栓16例，近期大手术史11例，肺癌1例，不明原因6例。34例均使用GE Light Speed Plus多层螺旋CT(MSCT)行平扫及造影增强扫描，1次采集4层图像。结果 分析34例共1824支肺动脉分支，其中507支肺动脉分支显示了栓塞，占27．8％。在680支肺段动脉中，246支显示了栓塞，占36．2％；而亚段肺动脉1041支中，141支显示了栓塞，占13．5％。平扫肺动脉栓塞的间接征象为肺纹理稀少19例，肺动脉高压2例，胸水16例，胸膜下梗死灶共41个，梗死灶多发11例，单发12例，双肺6例。1例慢性栓塞栓子钙化，极为少见。造影增强后肺动脉栓塞的直接征象为不同程度的肺动脉分支充盈缺损。充盈缺损有4种表现形式：中心型57支，偏心型160支，附壁血栓131支，完全阻塞型159支。结论 多层螺旋CT肺动脉造影是诊断肺动脉栓塞的快速、有效、无创伤的诊断方法，尤其对亚段肺动脉栓塞是一种先进的方法，可以代替肺动脉造影，可与电子束CT媲美，可能成为诊断肺动脉栓塞的首选方法。